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'High-fat' (Omega-6-rich, Omega-3 deficient) maternal diet can cause life-long changes in the fetal brain

Medical University of Vienna


When pregnant women consume diets high in polyunsaturated omega-6 fatty acids, an excess of endocannabinoids is produced which overloads the fetus, and impairs healthy brain development.


We've modified the title of this (otherwise pretty good) news article from Neuroscience News, as:

  1. Using the term 'High-Fat' to describe ANY kind of diet is so vague as to be useless - because there are many different kinds of fats, each with very different effects on health
  2. as used here, that term seems particularly misleading, given that the effects found relate specifically to the high omega-6 polyunsaturated fat (PUFA) content of the study diet (as the article itself does at least mention, and explain fairly well)
Calling it a 'high fat diet' in the headline (as so many articles always do) effectively conceals the fact that the effects found were the direct result of the excess of omega-6 relative to omega-3 PUFA - which is a key characteristic of typical modern, western-type diets.

It is these fats from which a whole array of different 'endocannabinoids' are made - and different ones are made from omega-6 fats, than from omega-3.

The effects shown involved lifelong impairments of brain function in the offspring of (animal) mothers eating this omega-6 rich (and therefore relatively omega-3 deficient) diet. 

Specifically - as already shown by previous research, the endocannabinoid-mediated effects of this omega-6/3 imbalance on the developing offspring's brain lead to:

  • permanent changes in brain networks, leading to an irreversible increase in anxiety and emotional dysregulation - and what's more
  • these kinds of brain changes are already known to raise risks for many developmental and psychiatric disorders, incuding not just anxiety, but ADHD, depression and schizophrenia.

Rather concerning is that this kind of diet is now eaten by most humans in all developed countries. 

It does seem highly unlikely that most pregnant women would actually want to confer permanent brain damage of this kind, with its associated risks, on their unborn children.   So it's very hard not to conclude that if most mothers-to-be actually knew that the diet they are eating could so this - they would probably be willing to try and eat differently.

Unfortunately, with headlines like this - and thousands of others over the years - all emphasising 'high fat', implying that fat alone (type unspecified) is the problem 'ingredient', they would NOT be getting the information they really need. 

If they only knew the facts - most would probably be willing to consume less omega-6 PUFA from vegetable oils (found in almost all processed foods) and more omega-3 from fish and seafood.

As it is - driven by endless misleading headlines like this one - they would probably instead be led to eat foods and diets promoted or labelled as 'low fat'. 

And ironically enough, that usually means processed foods, high in sugar and refined carbohydrates, often with undesirable artiifical additives - and with what fats they do contain coming from cheap vegetable oils....   rich in omega-6, and lacking omega-3.

For details of this research, see:

The same research is also covered in this news article (for which again, we have modified the title to make it more accurate):

A study team at MedUni Vienna’s Center for Brain Research has found that high-fat maternal diets can cause life-long changes in the brain of the unborn offspring.

When a pregnant woman consumes a diet high in polyunsaturated omega-6 fatty acids, her body produces an excess of endogenous cannabinoids (endocannabinoids), which overload the fetal organism and impair the development of healthy brain networks.

Such a mechanism seems relevant to pathologies such as ADHD, schizophrenia and anxiety disorders. It is unlikely that such damage can simply be reversed by a subsequent change of diet.

The study, which has been published in the journal ‘Molecular Psychiatry’, examined in cell- and mouse models, how intake of high-fat diets throughout pregnancy (rich in polyunsaturated omega-6 fatty acids) impacts fetal brain development.

When the mother consumes a high-fat diet during pregnancy, both mother and child produce an excess of endocannabinoids, which can even be transferred from the mother to the fetus. Endocannabinoids can then overload the corresponding cannabinoid receptors in the fetal brain and limit their ability to signal. As a result, nerve cells will no longer be able to correctly integrate into the brain to fulfil their prospective functions.

The study also shows that these impairments persist throughout life of the affected offspring and can serve as critical triggers to developing psychiatric disorders later in life.

Endocannabinoids are substances produced by the body itself. They are part of the endocannabinoid system, which serves as a fundamental communication system in the brain as well as other organs. In the adult brain, endocannabinoids limit communication (‘chemical neurotransmission’) between neurons by binding to cannabinoid receptors.

In the developing brain, endocannabinoids determine when and where neurons are positioned and if they form connections with each other. This means that any substance that influences either endocannabinoid levels or directly affects cannabinoid receptor function will inevitably impinge upon brain development.

“By acting like a ‘stop signal’, a prolonged overload of endocannabinoids impairs the developmental program of many neurons in the fetal brain,” explains principal investigator Tibor Harkany, Head of the Department of Molecular Neurobiology at MedUni Vienna’s Center for Brain Research.

“Persistently muting cannabinoid receptors, we believe, alters the epigenetic programs of affected nerve cells. Epigenetic mechanisms determine the pattern of gene expression in any cell. If damaged, the cells are no longer able to carry out their functions adequately. This will limit their ability to adapt their proper shape or select communication partners because of a shortage of proteins required as cellular building blocks or signalling molecules.”

On a large scale, an inhibition to the creation of connections between brain cells will impair the formation of important neuronal networks, the functional building blocks of the brain. This can result in psychiatric disorders such as ADHD, schizophrenia and anxiety disorders.

The study also shows that these impairments persist throughout life of the affected offspring and can serve as critical triggers to developing psychiatric disorders later in life. The image is in the public domain.

Damage is likely irreversible

“As far as we can tell, the pathological changes of nerve cells we have found are irreversible,” explains Harkany. “It is of limited use to changing to a healthy, low-fat diet after birth when the damage has already been done.”

Although the study is based on animal models, Harkany stresses that other studies already indicate harmful effects in humans, while this report identifies the very molecular mechanisms that can also apply to humans.

Is treatment still possible?

“In order to find effective treatments, we will need active agents that directly intervene in the epigenetic regulation of gene expression,” explains lead author Valentina Cinquina. “We have not yet trialed any such drugs but it is an exciting prospect to work on such interventions, which can perhaps be used safely and effectively in the future.” For example, so-called histone deacytylase Inhibitors (HDACs) are extensively tested for their treatment potential in Alzheimer’s disease and various cancers.